Cooperative supramolecular polymerization of a perylene diimide derivative and its impact on electron-transporting properties

Abstract

H-bonding-promoted supramolecular polymerization of a perylene diimide (PDI) building block and its impact on charge carrier mobility were studied. PDI-1, containing a carboxylic acid group, exhibits H-aggregation in a non-polar solvent decalin while in THF or chloroform it remains in the monomeric form. In contrast, the control molecule PDI-2, containing an ester group does not show aggregation even in decalin, indicating that H-bonding among the carboxylic acid is primarily responsible for H-aggregation, which is further verified by the FT-IR study. A variable temperature UV/Vis study establishes a cooperative pathway for the supramolecular polymerization of PDI-1. Microscopy images show a short fibrillar morphology. Flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements reveal significantly higher electrical conductivity for the PDI-1 film prepared from decalin compared with that prepared from THF/MeOH or the film of non-aggregated PDI-2 prepared from decalin. By combining the transient absorption spectroscopy data (that estimate the charge carrier generation efficiency) and the TRMC evaluated conductivity, the 1D charge carrier mobility of PDI-1 (μ_e,1D) is estimated to be 0.24 cm² V⁻¹ s⁻¹, which is among the top values reported for any PDI derivative measured using the same technique.